Unit 1-Bonding Topic 3
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What is an ionic bond?
Ionic bond is the electrostatic attraction between positive and negative ions.
What is meant by an ionic lattice?
A lattice is a regular arrangement of ions where each positive ion is surrounded by negative ions and each negative ion is surrounded by positive ions.
Explain the physical properties of ionic compounds: • melting point and boiling point • solubility (water molecules surround ions) • electrical conductivity
• Ionic compounds have high melting and boiling points because strong ionic bonds must be broken in order to break down the lattice. • Tend to be soluble in water. • Ionic compounds conduct electricity only when molten or in solution, due to the breakdown of the lattice resulting in the ions being free to move
What is a covalent bond?
In a covalent bond, the shared pair of electrons is attracted to the nuclei of the two bonded atoms. Covalent bonds are usually between non metals.
Draw a diagram, showing all outer electrons, to represent a molecule of Arsenic Chloride, AsCl3.
What are the two types of covalent structures??
Covalent substances can form either discrete molecular or giant network structures.
Which elements exist as diatomic molecules?
HINFOClBr Hydrogen, Iodine, Nitrogen, Fluorine, Oxygen, Chlorine and Bromine
Name these shapes of molecules.
• Linear 2. angular(Bent) • trigonal pyramidal 4. tetrahedral.
Explain the physical properties of discrete molecular covalent compounds: • melting point and boiling point • solubility (water) • electrical conductivity
• Covalent molecular substances have low melting and boiling points as only weak forces of attraction between molecules are being broken. • Covalent molecules tend to be insoluble in water but soluble in covalent type solvents. • Covalent molecules never conduct except carbon graphite.
Explain the physical properties of covalent network compounds: • melting point and boiling point • solubility (water molecules surround ions) • electrical conductivity
• Giant covalent network structures have very high melting and boiling points because the network of strong covalent bonds must be broken. • Covalent molecules tend to be insoluble in water but soluble in covalent type solvents. • Covalent molecules never conduct except carbon graphite.
Describe the bonding in metals.
In metallic bonding, the outer electrons are delocalised (free to move). This produces an electrostatic force of attraction between the positively charged metal ions, and the negatively charged delocalised electrons.
Explain the physical properties of metals. • Melting and boiling points • Conductivity of electricity
• Metals are held together by strong forces and have high melting and boiling points. • The ability of metals to conduct electricity stems from their delocalised electrons. As these are free to move, an electrical current can flow through metallic materials.
Which type of bonding matches each line in the table?
A= Discrete covalent molcular B = Covalent network C = Ionic D = Metallic
Which type of bonding is represented by each diagram?
A = Metallic B = Discrete covalent molecular C = Covalent network D = Ionic
How are Ionic bonds held together by?
the electrostatic attraction between positive and negative ions.
Metal ions are ______ charged
Positively
Non-metal ions are ____________ charged
Negatively
Metal atoms donate electrons to form positively charged ions. So non metal atoms gain electrons to __________
form negatively charged ions
Ionic compounds only conduct when molten or in solution as the
ions are free to move